The present invention relates to an electronic whiteboard and a penholder used for the same, and more particularly to marker-color-changing in a penholder fitting or incorporating a marker pen, in an electronic whiteboard for storing the information drawn on a board by using a marker pen into a personal computer (hereinafter called computer) by using a sound wave. Herein, the electronic whiteboard makes use of acoustic-coordinates-input-technology (hereinafter called digitizing technology) of plane input type.
Recently, the digitizer is widely used for picking up coordinates by pointing the design drawing adhered on a board by using a pen dedicated for the digitizer, and putting the design drawing into the computer.
This pen has a dedicated function of emitting an ultrasonic wave and infrared light, and sends the ultrasonic wave and infrared light to sensors disposed at both ends in the width direction of the upper end of the board. The pointing position on the board is transmitted from the sensors to the computer and is stored as data.
This technology is also applied in the so-called electronic whiteboard.
FIG. 5 is a schematic structural diagram of an electronic whiteboard making use of the conventional digitizing technology.
In the electronic whiteboard shown in FIG. 5, four penholders 102a, 102b, 102c, 102d hold black, red, blue and green marker pens for whiteboard, and have function of emitting infrared light and an ultrasonic wave. The penholders 102a, 102b, 102c, 102d transmit infrared light and the ultrasonic wave to sensors 103a and 103b disposed at both ends in the width direction of the upper end of a board 101.
The sensors 103a, 103b receive the infrared light and ultrasonic wave. Depending on the time difference of receiving the infrared light and ultrasonic wave in the sensors 103a, 103b, the distance from the penholder 102a to the sensors 103a, 103b is calculated. The obtained data is transferred to a computer 104. The computer 104 calculates the position of the penholder 102a on the board 101 by trigonometry, and shows the position information of the penholder 102a on a display unit.
In the electronic whiteboard of such structure, the position information of the penholder 102a and others is instantly shown on the computer display, and the drawing information on the board 101 is stored in the computer.
In the electronic whiteboard shown in FIG. 5, when using black, red, blue, and green colors, to change the colors to be drawn on the board 101, four penholders 102a to 102d corresponding to the colors are needed. That is, the penholders are required as many as the number of colors. Since the penholders have the costly function of emitting infrared light and an ultrasonic wave, it leads to increase of cost.
Further, if the user mounts a marker pen of a wrong color, drawing information of a different color is stored in the computer. Or if one penholder is broken, the specific color cannot be used.
The electronic whiteboard of the invention includes a penholder for mounting marker pens, and an electronic whiteboard main body.
An infrared light emitting unit of the penholder emits infrared light containing the color information of marker pen, an ultrasonic wave emitting unit emits an ultrasonic wave, and color changeover means changes over the color information depending on the color of marker pen.
The electronic whiteboard main body receives the infrared light and ultrasonic wave emitted from the penholder, and determines the position of the penholder depending on the reception timing of the infrared light and ultrasonic wave.
The electronic whiteboard main body includes plural sensors. The plural sensors receive the infrared light and ultrasonic wave. Depending on the time difference of the reception timing of the ultrasonic wave in the plural sensors, the electronic whiteboard main body issues the information about the position of the penholder.
By this invention, the number of penholders is decreased by changing over the color information of the infrared light to be emitted according to the color of the marker pen being used.
At the same time, error by the user mounting a wrong marker pen is prevented.